Blue laser diodes and LEDs based on II-VI semiconductor heterostructures

The authors report the first observation of blue stimulated emission from a semiconductor laser structure. At 77 K, under pulsed current injection, the laser devices output light in the blue spectral region at wavelengths as short as 475.4 nm (2.606 eV). The laser structure consists of a single separate-confinement approximately 200-AA quantum well of Zn/sub 0.85/Cd/sub 0.17/Se centered in a ZnSe light-guiding layer (1- mu m thick). Top ( approximately 1.0 mu m) and bottom ( approximately 1.5 mu m) cladding layers of ZnS/sub 0.1/Se/sub 0.9/, along with the ZnSe light-guiding layers, were doped p-type and n-type, respectively. All of the major constituents of the various layers of the heterostructure were grown by MBE (molecular beam epitaxy) using elemental Zn, Cd, Se, and S. LEDs (light emitting diodes) have also been fabricated which emit bright blue light (dominant wavelength as short as 479 nm) at room temperature. The p-on-n heterostructure LEDs exhibit excellent electrical properties as well: mesa devices (area=3*10/sup -3/ cm/sup 2/) produce 25 mA at 4.4 V at 300 K. Green and blue/green LEDs have also been fabricated and studied.